The proposed work involves a combined clinical and laboratory investigation of drug toxicological effects in the newborn. The process of drug transfer from mother to fetus and neonate will be studied (placental transfer, breast milk transfer). The pathways of drug metabolism will be studied in the neonate, with emphasis upon routes which provide toxic metabolites. The molecular basis of drug toxicity will be studied. The effects of chronic anticonvulsant therapy for the mother on fetal development will be investigated further. Work on the biochemical characterization of the newborn will aid in understanding observed toxic effects. Attempts will be made to find safer drugs and to reduce the hazards of drug toxicity and drug-drug interaction in the newborn.